Yamada Nagito is an occult maniac, who went to Tokyo to attend uni.
Founding a 3-story cheap building, which is said to grant wishes, he was elated.

"The architect who built this became famous, the illustrator who moved in became busy and moved closer to the city, and the young couple that was living here until last month gave birth to a baby, which led to this becoming open. You are quite lucky", he was told.

However, when he moved in, things started to be a little...eerie
Squeaking, and screeching sound of old doors at 2 am, when all windows and doors should be closed.
He stands up from the bed and makes his way to the living room, the sound stops.

If that's all then it's alright. It's an old house, after all but...
He has found a huge scratch on the stars in shape of 七 (seven).
六 (Six) near the bath, 五 (five) near the toilet.
Wait, is it a countdown?
and what for?

Panicking, he left the house, running to a manga cafe.
With no one to turn to, he decide to arrange an offline meeting on occult forums he's on, "Ikaigabuchi", there, the fortuneteller he's familiar with has said, "you have mark of the meeting...and it's a girl too...wait isn't she dead?"

There's a prequel listed on LNDB but I ain't sure how it's related:
Yu-shiki from GAGAGA